MESOSCALE PRECIPITATION DISCUSSION 0159
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
419 PM EDT THU MAY 17 2018

AREAS AFFECTED...LOWER TO MID-MISSISSIPPI VALLEY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 172018Z - 180130Z

SUMMARY...A FLASH FLOOD THREAT WILL CONTINUE FOR THE NEXT 3-6
HOURS IN THE VICINITY OF THE LOWER TO MID-MISSISSIPPI VALLEY WITH
SLOW MOVING REPEATING CORES OF HEAVY RAIN. ADDITIONAL RAINFALL OF
3-5 INCHES WILL BE POSSIBLE ON A LOCALIZED BASIS.

DISCUSSION...MID-LEVEL WATER VAPOR IMAGERY DEPICTED AN ELONGATING
BUT SLOW MOVING DOUBLE BARREL VORTICITY MAX OVER THE
ARKANSAS/MISSISSIPPI BORDER AT 2000Z. SURFACE OBSERVATIONS PLACED
A LOW CENTER NEAR HKA WITH A WEAKENING STATIONARY FRONT EXTENDING
EAST AND SOUTH TO SOUTHWEST OF THE LOW. IN ADDITION...AN INVERTED
TROUGH AXIS EXTENDED NORTH-NORTHWEST OF THE LOW INTO SOUTHEASTERN
MISSOURI. OBSERVED CONVECTION OVER THE PAST FEW HOURS IN THE
VICINITY OF THE SURFACE LOW AND RELATED BOUNDARIES HAS BEEN SLOW
MOVING...GENERALLY TOWARD THE WEST...WITH REPEATING CELL MOTIONS.
KPAH AND KNQA RADAR RATES HAVE PEAKED AS HIGH AS 2-3 IN/HR...BUT
THE LOCALIZED NATURE OF THESE ESTIMATED RATES ALONG WITH LIKELY
EMBEDDED SMALL HAIL HAS MADE CONFIRMING WITH GROUND TRUTH
DIFFICULT. NONETHELESS...PRECIPITABLE WATER VALUES OF ROUGHLY 1.7
TO 1.8 INCHES PER RECENT GPS SITES AND MLCAPE AT OR ABOUT 1000
J/KG PER THE SPC MESOANALYSIS PAGE SUPPORT THE POTENTIAL FOR 2+
IN/HR RAIN RATES GIVEN THE SLOW STORM MOTIONS.

ADDITIONAL CONVECTION IS EXPECTED OVER THE NEXT 3-6 HOURS...MAINLY
NORTH AND EAST OF THE VORTICITY MAXIMA...WHERE BETTER ACCESS TO
MOISTURE AND WEAK UPPER LEVEL DIFFLUENCE  WILL BE PRESENT. IN
ADDITION...EASTERLY TO SOUTHEASTERLY LOW TO MID-LEVEL MEAN FLOW
WILL SUPPORT CONTINUED REPEATING OF CELLS UNTIL LOSS OF DAYTIME
HEATING/INSTABILITY BEYOND SUNSET WITH THE POTENTIAL FOR AN
ADDITIONAL 3-5 INCHES OF RAIN ON A LOCALIZED BASIS ALONG WITH
FLASH FLOODING.

OTTO

ATTN...WFO...HUN...LMK...LSX...MEG...OHX...PAH...SGF...

ATTN...RFC...LMRFC...NCRFC...OHRFC...SERFC...

LAT...LON   38239019 38008988 37708971 37448936 37258882
            37168809 36938730 36588700 35978702 34708789
            34238824 33928879 33998964 34739032 36139090
            37689117 38109091